Optical disk device and information recording/reproducing method

ABSTRACT

An optical disk device is provided with an optical pickup that includes a convergent optical system having an objective lens for converging a light beam emitted from the laser light source to form a microspot on an optical disk and an aberration correcting optical system for controlling a spherical aberration of the convergent optical system, and performs information recording or reproduction with respect to a multi-layer optical disk having at least a first recording layer and a second recording layer. In the optical disk device, an operation of changing a correction quantity of the spherical aberration from a value adequate for the first recording layer to a predetermined value is started before an operation of moving a focus position of the microspot from the first layer to the second layer is completed. This allows a focus control to be performed stably with respect to the second recording layer in a state in which the spherical aberration correction already has been carried out, thereby preventing the focus control from failing due to an unsuccessful interlayer jump.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 10/894,888, filedJul. 20, 2004, which is a Division of application Ser. No. 09/946,645,filed Sep. 4, 2001, now U.S. Pat. No. 6,954,417, which applications areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an optical information device(hereinafter referred to as “optical disk device”) provided with anoptical pickup for recording, reproducing, or erasing information on anoptical disk-as an optical information medium, and to arecording/reproducing method for recording, reproducing, or erasinginformation on the optical disk. Herein, the “recording/reproducing”refers to an apparatus or method capable of carrying out one or bothfunctions for the purposes of the present invention. Besides, thepresent invention also relates to various systems in which the foregoingoptical disk device is utilized.

2. Related Background Art

An optical memory technology in which an optical disk having pit-likepatterns is used as a high-density, large-capacity memory medium hasbeen put to practical use while the technology has been applied in anincreasingly wide range of fields including digital audio disks, videodisks, document file disks, and data files. Functions required forcarrying out the recording and reproduction of information to and froman optical disk with high reliability are classified roughly into alight collecting function for forming a microspot at a diffractionlimit, focus control (focus servo) and tracking control functions of anoptical system, and a pit signal (information signal) detectingfunction.

Recently, a technique of increasing a numerical aperture (NA) of anobjective lens that forms a microspot at a diffraction limit on anoptical disk by converging an optical beam has been examined with a viewto obtaining an even higher recording density of an optical disk.However, a spherical aberration stemming from an error of a thickness ofa substrate that protects a recording layer of the optical disk isproportional to the NA raised to the fourth power. Therefore, in thecase where the NA is set to be great, for instance, 0.8 or 0.85, it isindispensable to provide a means for correcting a spherical aberrationin an optical system. An example of the same is shown in FIG. 14.

In a pickup 11 shown in FIG. 14, 1 denotes a laser light source as aradiation source. A light beam (laser beam) emitted from the laser lightsource 1 is converted into parallel light by a collimator lens 3, passesthrough a liquid crystal aberration correcting element (aberrationcorrecting optical system) 4, enters the objective lens 5, and isconverged and directed to an optical disk 6. The light beam reflected bythe optical disk 6 goes backwards along the foregoing optical path, andis converged by the collimator lens 3. Then, the light is guided by alight dividing means such as a diffracting element 2 towardphotodetectors 9 and 10, and is incident thereto. By calculatingelectric outputs according to respective quantities of light incident onthe photodetectors 9 and 10, servo signals (focus error signal andtracking error signal) and an information signal can be obtained. Here,the NA of the objective lens 5 is at least 0.8.

Though not shown, the objective lens 5 is provided with a driving meanssuch as a coil and a magnet, for the focus control for controlling aposition of the objective lens in the optical axis direction and thetracking control for controlling a position of the objective lens in adirection perpendicular to the optical axis direction. Besides, thoughnot shown in the figures, either, a transparent substrate is providedover an objective-lens-5-side surface of an information recording layerof the optical disk 6, so that information is protected. Since errors inthe thickness and the refractive index of the transparent substrate leadto spherical aberrations, the liquid crystal aberration correctingelement 4 corrects a wavefront of the light beam so that reproductionsignals are obtained in the optimal state. On the liquid crystalaberration element 4, patterns of transparent electrodes such as ITO areformed, and by applying voltages to the transparent electrodes, thein-plane refractive index distribution of the liquid crystal aberrationcorrecting element 4 is controlled so that the wavefront of the lightbeam is modulated.

An optical disk device 116 in which such an optical pickup 11 as aboveis used is shown in FIG. 15. In FIG. 15, 8 denotes an aberrationcorrecting element driving circuit for applying a voltage to the liquidcrystal aberration correcting element 4, 117 denotes a motor forrotating an optical disk 6, and 118 denotes a control circuit forreceiving signals obtained from the optical pickup 11 and controllingand driving the motor 117, the objective lens 5, the aberrationcorrecting element driving circuit 8, and the laser light source 1. Thecontrol circuit 118 causes the laser light source 1 to emit light,drives the motor 117 so as to rotate the optical disk 6, and controlsthe objective lens 5 according to signals obtained from the opticalpickup 11. Furthermore, the control circuit 118 drives the aberrationcorrecting element driving circuit 8 so as to improve informationsignals obtained from the optical pickup 11.

An optical system used as the optical pickup 11 in the optical diskdevice 116 is not limited to the optical system shown in FIG. 14, butmay be an optical system disclosed by JP 2000-131603A, which is shown inFIG. 16.

In FIG. 16, a laser light source, a collimator lens, and photodetectorsof the optical system as the optical pickup are omitted. These may beconfigured in the same manner as in the optical system shown in FIG. 14.A light beam converted into a parallel light by a collimator lens, notshown, passes through an aberration correcting lens group 201 composedof a negative lens group 21 and a positive lens group 22, and isconverged and directed to the optical disk 6 by an objective lens group202 composed of a pair of a first objective lens 23 and a secondobjective lens 24. By changing a distance between the negative lensgroup 21 and the positive lens group 22 of the aberration correctinglens group 201, the spherical aberration of the optical system as awhole is corrected. To change the distance between the negative lensgroup 21 and the positive lens group 22, for instance, the lens groupsmay be provided with a driving means 25 and a driving means 26 formoving the same, respectively. Each of the driving means 25 and 26 maybe formed with a voice coil, a piezoelectric element, an ultrasonicmotor, or a screw feeder.

In the foregoing configuration, normally, the spherical aberrationcorrection is carried out so as to improve the quality of theinformation signals on the premise that the focus control stablyfunctions on a single information recording surface of the optical disk6.

However, according to the DVD standard with an objective lens having anNA of 0.6, a two-layer disk having two information recording surfacesalso is adaptable. Therefore, with an NA set to be greater, likewise thetwo-layer disk structure is effective so as to further increase thememory capacity per one optical disk. A two-layer disk 61 is composed ofa substrate 62, an L0 layer (first recording layer) 63, an intermediatelayer 65, an L1 layer (second recording layer) 64, and a protectivelayer 66 on a reverse side, which are laminated in the stated order fromthe optical pickup 60 side, as shown in FIG. 17. The substrate 62 andthe intermediate layer 65 are made of a transparent medium such as aresin. Since the intermediate layer 65 is provided between the L0 layer63 and the L1 layer 64, a thickness from the-optical-pickup-60-sidesurface of the optical disk 61 to the L1 layer 64 is greater than athickness therefrom to the L0 layer 63 by the thickness of theintermediate layer 65. This thickness difference generates a sphericalaberration. In the case of an optical system according to the DVDstandard in which the objective lens has an NA of 0.6, however, theforegoing spherical aberration is within a tolerance, thereby making itpossible to record/reproduce information without aberration correction.

In the case where an objective lens with a great NA of not less than 0.8is used so as to further increase the recording density, a sphericalaberration due to the thickness of the intermediate layer 65 cannot beignored. In other words, it is impossible to record/reproduceinformation with respect to both recording layers with a common opticalpickup without correcting a spherical aberration. In the case where theNA is increased to not less than 0.8, as described above, a sphericalaberration correcting means is provided even in the case whereinformation recording/reproduction is carried out with respect to asingle recording layer. Therefore, in the case where therecording/reproduction is carried out with respect to the two-layer diskas shown in FIG. 17, the spherical aberration due to the thickness ofthe intermediate layer 65 is cancelled by optimally carrying out thespherical aberration correction with respect to each recording layer.

To the two-layer disk as shown in FIG. 17, a position at which a lightbeam is converged thereby forming a microspot (hereinafter referred toas focus position) occasionally is moved: for instance, from the L0layer 63 to the L1 layer 64 while information is beingrecorded/reproduced to/from the L0 layer with the light beam convergedonto the L0 layer 63, so that information is recorded/reproduced to/fromthe L1 layer 64; or to the contrary, from the L1 layer 64 to the L0layer 63. (Such an operation of moving the focus position to anotherrecording layer is hereinafter referred to as “interlayer jump”.) JP9(1997)-115146A, JP10(1998)-143873A, JP11(1999)-191222A andJP11(1999)-316954A disclose techniques of devising a pulse or an offsetsignal to be applied to a focus error signal, so as to stabilize thefocus control upon such an interlayer jump.

The foregoing documents, however, do not disclose an idea that acorrection quantity of the spherical aberration is changed for eachrecording layer upon an interlayer jump. In the case where the NA is notless than 0.8, when an interlayer jump is made without changing thespherical aberration correction quantity, the following problems arise.

FIG. 18 is a flowchart illustrating an operation when an interlayer jumpis carried out. When the control circuit issues an interlayer jumpcommand (or the control circuit receives an interlayer jump command fromanother circuit) while a recording/reproducing operation is carried outwith the focus control being conducted with respect to a first recordinglayer (hereinafter referred to as “first layer”) (Step 901), the controlcircuit generates an interlayer jump signal (Step 902), the focusposition is moved to the second recording layer (hereinafter referred toas “second layer”) (Step 903), and a recording/reproducing operation iscarried out to a second layer (Step 904). FIG. 19 is a timing chart ofrespective signals in the foregoing operation. The interlayer jumpsignal varies in response to a signal corresponding to the interlayerjump command at Step 901 as a trigger (Step 902). The interlayer jumpsignal is, as shown in the figure, composed of a kick pulse KP forleaving a loop for focus control with respect to the first layer andstarting to move the objective lens so that the focus position is movedto the second layer, and a brake pulse BP for stopping the moving of theobjective lens and entering a loop for focus control with respect to thesecond layer.

In such an interlayer jump operation, during the recording/reproductionwith respect to the first layer before a jump, the spherical aberrationcorrection quantity is optimal with respect to the first layer.Therefore, if the focus position is moved to the second layer withoutany change to the correction state of the spherical aberration, aspherical aberration occurs due to the thickness of the intermediatelayer 65 between the first and second layers. This results in thedeterioration of the focus control signal (the deterioration of theamplitude and linearity of the focus error (FE) signal, the occurrenceof an offset, etc.), thereby making the focus control with respect tothe second layer unstable. Further, though it is effective to refer to amagnitude of a reproduction signal so as to confirm whether or not thefocus control functions normally, this also raises the followingproblem. Namely, if a spherical aberration occurs when the focusposition is moved to the second layer, the reproduction signal has asmaller amplitude, thereby making it impossible to check whether or notthe focus control is carried out normally.

SUMMARY OF THE INVENTION

Therefore, to solve the aforementioned problems, it is an object of thepresent invention to provide a stable interlayer jump by improvingoperations of an optical system that performs the focus position movingand the spherical aberration correction upon an interlayer jump, in thecase where the numerical aperture (NA) of an objective lens thatconverges a light beam to form a microspot at the diffraction limit onan optical disk is increased to not less than 0.8 and information isrecorded/reproduced to/from a multi-layer optical disk having not lessthan two recording layers by making interlayer jumps in order to obtaina higher recording density of an optical disk.

To achieve the foregoing object, the present invention has the followingconfiguration.

An optical disk device of the present invention comprises: an opticalpickup including a laser light source, a convergent optical systemhaving an objective lens that receives a light beam emitted from thelaser light source and converges the same to form a microspot on anoptical disk, a photodetector that receives the light beam reflectedfrom the optical disk and outputs an electric signal according to aquantity of the received light, and an aberration correcting opticalsystem that controls a spherical aberration of the convergent opticalsystem; a motor that rotates the optical disk; and a control circuitthat receives a signal obtained from the optical pickup, and controlsand drives the laser light source, the objective lens, the aberrationcorrecting optical system, and the motor. Besides, the optical diskdevice performs information recording or reproduction with respect to amulti-layer optical disk having at least a first recording layer and asecond recording layer, the optical disk device. The optical disk deviceis characterized in that an operation of changing a correction quantityof the spherical aberration from a value adequate for the firstrecording layer to a predetermined value is started before an operationof moving a focus position of the microspot from the first layer to thesecond layer is completed.

This ensures that the spherical aberration correction adequate for thesecond layer has been carried out when the focus control with respect tothe second layer is performed. Therefore, this allows the focus controlto be performed stably, thereby preventing the focus control fromfailing due to an unsuccessful interlayer jump.

A first preferable configuration of the optical disk device of thepresent invention is characterized in that the operation of moving thefocus position of the microspot and the operation of changing thecorrection quantity of the spherical aberration are startedsubstantially simultaneously.

By starting the operation of moving the focus position from the firstlayer to the second layer substantially simultaneously when theoperation of changing the correction quantity of the sphericalaberration is started, the interlayer jump can be carried out in a shorttime.

A second preferable configuration of the optical disk device of thepresent invention is characterized in that the operation of changing thecorrection quantity of the spherical aberration is started before theoperation of moving the focus position of the microspot is started.

This allows the spherical aberration correction adequate for the secondlayer substantially to be completed by the time the focus control isperformed with respect to the second layer, thereby allowing the focuscontrol to be performed stably without being affected adversely by thespherical aberration. Therefore, this more certainly prevents the focuscontrol from failing due to an unsuccessful interlayer jump.

In the second preferable configuration of the optical disk device, theoperation of moving the focus position of the microspot preferably isstarted after the operation of changing the correction quantity of thespherical aberration is completed.

This allows the spherical aberration correction adequate for the secondlayer to be completed with certainty by the time the focus control isperformed with respect to the second layer, thereby allowing the focuscontrol to be performed stably without being affected adversely by thespherical aberration. Therefore, this most certainly prevents the focuscontrol from failing due to an unsuccessful interlayer jump.

In the first and second preferable configurations of the optical diskdevice, the operation of changing the correction quantity of thespherical aberration preferably is completed during the operation ofmoving the focus position of the microspot.

By completing the operation of changing the correction quantity of thespherical aberration before the focus position reaches the second layer,the focus control can be performed more stably with respect to thesecond layer.

Furthermore, in the first and second preferable configurations of theoptical disk device, the operation of moving the focus position of themicrospot preferably is completed before the operation of changing thecorrection quantity of the spherical aberration is completed.

In the case where it takes much time to change the correction quantityof the spherical aberration, the time required for carrying out aninterlayer jump is shortened by completing the operation of moving thefocus position to the second layer before the operation of changing thecorrection quantity of the spherical aberration is completed.

Furthermore, in the foregoing optical disk device of the presentinvention, the quantity of a change in the correction quantity of thespherical aberration preferably is according to a standard thickness ofan intermediate layer between the first recording layer and the secondrecording layer.

This allows the focus control with respect to the second layer to beperformed stably, thereby allowing a recording or reproducing operationto be performed on the second layer immediately after an interlayerjump. Besides, a setup time following the loading of an optical disk inthe optical disk device or the turning on of the optical disk device canbe shortened.

Alternatively, in the optical disk device of the present invention, aquantity of a change in the correction quantity of the sphericalaberration may be according to approximately half of a standardthickness of an intermediate layer between the first recording layer andthe second recording layer.

This ensures the stability of the focus control with respect to thefirst layer before an interlayer jump. Particularly in the case wherethe operation of changing the correction quantity of the sphericalaberration is started before the operation of moving the focus position,a significant effect that the focus control to the first layer isstabilized and the focus control is prevented from failing can beachieved. Besides, a setup time following the loading of an optical diskin the optical disk device or the turning on of the optical disk devicecan be shortened.

Furthermore, in the optical disk device of the present invention, aquantity of a change in the correction quantity of the sphericalaberration preferably is a difference between a correction quantity of aspherical aberration adequate for the first recording layer and acorrection quantity of a spherical aberration adequate for the secondrecording layer, which are obtained by learning when the multi-layerdisk is loaded in the optical disk device or when the optical diskdevice is turned on.

This allows the focus control with respect to the second layer to beperformed stably, thereby allowing a recording or reproducing operationto be performed on the second layer immediately after an interlayerjump. Besides, by previously learning a quantity of a change in thecorrection quantity of the spherical aberration that is necessary uponan interlayer jump, it is possible to realize a more stable interlayerjump.

Alternatively, the quantity of a change in the correction quantity ofthe spherical aberration may be approximately half of a differencebetween a correction quantity of a spherical aberration adequate for thefirst recording layer and a correction quantity of a sphericalaberration adequate for the second recording layer, which are obtainedby learning when the multi-layer disk is loaded in the optical diskdevice or when the optical disk device is turned on.

This ensures the stability of the focus control with respect to thefirst layer before an interlayer jump. Particularly in the case wherethe operation of changing the correction quantity of the sphericalaberration is started before the operation of moving the focus position,a significant effect in which the focus control to the first layer isstabilized and the focus control is prevented from failing can beachieved. Besides, by previously learning a quantity of a change in thecorrection quantity of the spherical aberration that is necessary uponan interlayer jump, it is possible to realize a more stable interlayerjump.

Next, an information recording/reproducing method of the presentinvention is a method for performing information recording orreproduction with respect to a multi-layer optical disk having at leasta first recording layer and a second recording layer by utilizing anoptical disk device. The optical disk device includes: an optical pickupincluding a laser light source, a convergent optical system having anobjective lens that receives a light beam emitted from the laser lightsource and converges the same to form a microspot on an optical disk, aphotodetector that receives the light beam reflected from the opticaldisk and outputs an electric signal according to a quantity of thereceived light, and an aberration correcting optical system thatcontrols a spherical aberration of the convergent optical system; amotor that rotates the optical disk; and a control circuit that receivesa signal obtained from the optical pickup, and controls and drives thelaser light source, the objective lens, the aberration correctingoptical system, and the motor. The method includes the steps of moving afocus position of the microspot from the first layer to the secondlayer, and changing a correction quantity of the spherical aberrationfrom a value adequate for the first recording layer to a predeterminedvalue, and is characterized in that the correction quantity changingstep is started before the focus position moving step is completed.

This ensures that the spherical aberration correction adequate for thesecond layer has been carried out when the focus control with respect tothe second layer is performed. Therefore, this allows the focus controlto be performed stably, thereby preventing the focus control fromfailing due to an unsuccessful interlayer jump.

A first preferable configuration of the recording/reproducing method ofthe present invention is characterized in that the focus position movingstep and the correction quantity changing step are started substantiallysimultaneously.

By starting the operation of moving the focus position from the firstlayer to the second layer substantially simultaneously when theoperation of changing the correction quantity of the sphericalaberration is started, the interlayer jump can be carried out in a shorttime.

A second preferable configuration of the recording/reproducing method ofthe present invention is characterized in that the correction quantitychanging step is started before the focus position moving step isstarted.

This allows the spherical aberration correction adequate for the secondlayer substantially to be completed by the time the focus control isperformed with respect to the second layer, thereby allowing the focuscontrol to be performed stably without being affected adversely by thespherical aberration. Therefore, this more certainly prevents the focuscontrol from failing due to an unsuccessful interlayer jump.

In the second preferable configuration of the recording/reproducingmethod, the focus position moving step preferably is started after thecorrection quantity changing step is completed.

This allows the spherical aberration correction adequate for the secondlayer to be completed with certainty by the time the focus control isperformed with respect to the second layer, thereby allowing the focuscontrol to be performed stably without being affected adversely by thespherical aberration. Therefore, this most certainly prevents the focuscontrol from failing due to an unsuccessful interlayer jump.

In the first and second configurations of the recording/reproducingmethod, the correction quantity changing step preferably is completedwhile the focus position moving step is being carried out.

By completing the operation of changing the correction quantity of thespherical aberration before the focus position reaches the second layer,the focus control can be performed more stably with respect to thesecond layer.

Furthermore, in the first and second preferable configurations of therecording/reproducing method, the focus position moving step preferablyis completed before the correction quantity changing step is completed.

In the case where it takes much time to change the correction quantityof the spherical aberration, the time required for carrying out aninterlayer jump is shortened by completing the operation of moving thefocus position to the second layer before the operation of changing thecorrection quantity of the spherical aberration is completed.

Furthermore, in the recording/reproducing method of the presentinvention, the quantity of a change in the correction quantity of thespherical aberration preferably is according to a standard thickness ofan intermediate layer between the first recording layer and the secondrecording layer.

This allows the focus control with respect to the second layer to beperformed stably, thereby allowing a recording or reproducing operationto be performed on the second layer immediately after an interlayerjump. Besides, a setup time following the loading of an optical disk inthe optical disk device or the turning on of the optical disk device canbe shortened.

Alternatively, in the recording/reproducing method of the presentinvention, the quantity of a change in the correction quantity of thespherical aberration may be according to approximately half of astandard thickness of an intermediate layer between the first recordinglayer and the second recording layer.

This ensures the stability of the focus control with respect to thefirst layer before an interlayer jump. Particularly in the case wherethe operation of changing the correction quantity of the sphericalaberration is started before the operation of moving the focus position,a significant effect in which the focus control to the first layer isstabilized and the focus control is prevented from failing can beachieved. Besides, a setup time following the loading of an optical diskin the optical disk device or the turning on of the optical disk devicecan be shortened.

In the recording/reproducing method of the present invention, thequantity of a change in the correction quantity of the sphericalaberration preferably is a difference between a correction quantity of aspherical aberration adequate for the first recording layer and acorrection quantity of a spherical aberration adequate for the secondrecording layer, which are obtained by learning when the multi-layerdisk is loaded in the optical disk device or when the optical diskdevice is turned on.

This allows the focus control with respect to the second layer to beperformed stably, thereby allowing a recording or reproducing operationto be performed to the second layer immediately after an interlayerjump. Besides, by previously learning the quantity of a change in thecorrection quantity of the spherical aberration that is necessary uponan interlayer jump, it is possible to realize a more stable interlayerjump.

Alternatively, the quantity of a change in the correction quantity ofthe spherical aberration may be approximately half of a differencebetween a correction quantity of a spherical aberration adequate for thefirst recording layer and a correction quantity of a sphericalaberration adequate for the second recording layer, which are obtainedby learning when the multi-layer disk is loaded in the optical diskdevice or when the optical disk device is turned on.

This ensures the stability of the focus control with respect to thefirst layer before an interlayer jump. Particularly in the case wherethe operation of changing the correction quantity of the sphericalaberration is started before the operation of moving the focus position,a significant effect that the focus control to the first layer isstabilized and the focus control is prevented from failing can beachieved. Besides, by previously learning the quantity of a change inthe correction quantity of the spherical aberration that is necessaryupon an interlayer jump, it is possible to realize a more stableinterlayer jump.

Next, a computer of the present invention includes: the optical diskdevice of the present invention; an input device or an input terminalfor inputting information; a computing device that performs acomputation based on at least one of information inputted through theinput device or the input terminal and information reproduced from theoptical disk device; and an output device or an output terminal fordisplaying or outputting at least one of information inputted throughthe input device or the input terminal, information reproduced from theoptical disk device, and a result of a computation of the computingdevice.

Since the optical disk device of the present invention is capable ofcarrying out an interlayer jump in a multi-layer optical disk stably andspeedily, the computer of the present invention is capable ofrecording/reproducing information stably and speedily.

Next, an optical disk player of the present invention includes: theoptical disk device of the present invention; and an information-imageconverting device for converting information signals obtained from theoptical disk device into images.

Since the optical disk device of the present invention is capable ofcarrying out an interlayer jump in a multi-layer optical disk stably andspeedily, the optical disk player of the present invention is capable ofrecording/reproducing information stably and speedily.

Next, an optical disk recorder of the present invention includes: theoptical disk device of the present invention; and an image-informationconverting device for converting image information into informationsignals that can be recorded by means of the optical disk device.

Since the optical disk device of the present invention is capable ofcarrying out an interlayer jump in a multi-layer optical disk stably andspeedily, the optical disk recorder of the present invention is capableof recording/reproducing information stably and speedily.

Next, an optical disk server of the present invention includes: anoptical disk device and a wireless input/output terminal. The opticaldisk device includes: an optical pickup including a laser light source,a convergent optical system having an objective lens that receives alight beam emitted from the laser light source and converges the same toform a microspot on an optical disk, a photodetector that receives thelight beam reflected from the optical disk and outputs an electricsignal according to a quantity of the received light, and an aberrationcorrecting optical system that controls a spherical aberration of theconvergent optical system; a motor that rotates the optical disk; and acontrol circuit that receives a signal obtained from the optical pickup,and controls and drives the laser light source, the objective lens, theaberration correcting optical system, and the motor.

This allows the optical disk server to communicate information with aplurality of devices having wireless receiving/transmitting terminals,for instance, computers, telephones, and TV tuners. Therefore, it ispossible to utilize the optical disk server as an information server(optical disk server) common to these plural devices.

In the optical disk server of the present invention, preferably, theoptical disk device performs information recording or reproduction withrespect to a multi-layer optical disk having at least a first recordinglayer and a second recording layer, and an operation of changing acorrection quantity of the spherical aberration from a value adequatefor the first recording layer to a predetermined value is started beforean operation of moving a focus position of the microspot from the firstlayer to the second layer is completed. In other words, the optical diskdevice composing the foregoing optical disk server of the presentinvention preferably is the optical disk device of the presentinvention.

Since the optical disk device of the present invention is capable ofcarrying out an interlayer jump in a multi-layer optical disk stably andspeedily, the preferable optical disk server of the present invention iscapable of recording/reproducing information stably and speedily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a procedure of a focus positionmoving operation and a spherical aberration correcting operation upon aninterlayer jump operation in an optical disk device according to a firstembodiment of the present invention.

FIG. 2 is a timing chart illustrating an example of variations ofrespective signals upon an interlayer jump operation in the optical diskdevice according to the first embodiment of the present invention.

FIG. 3 is a timing chart illustrating another example of variations ofrespective signals upon an interlayer jump operation in the optical diskdevice according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating a procedure of a focus positionmoving operation and a spherical aberration correcting operation upon aninterlayer jump operation in an optical disk device according to asecond embodiment of the present invention.

FIG. 5 is a timing chart illustrating an example of variations ofrespective signals upon an interlayer jump operation in the optical diskdevice according to the second embodiment of the present invention.

FIG. 6 is a timing chart illustrating another example of variations ofrespective signals upon an interlayer jump operation in the optical diskdevice according to the second embodiment of the present invention.

FIG. 7 is a timing chart illustrating still another example ofvariations of respective signals upon an interlayer jump operation inthe optical disk device according to the second embodiment of thepresent invention.

FIG. 8 is a timing chart illustrating still another example ofvariations of respective signals upon an interlayer jump operation inthe optical disk device according to the present invention.

FIG. 9 is a schematic perspective view illustrating a multi-layeroptical disk having four recording layers.

FIG. 10 is a view illustrating a schematic configuration of a computeraccording to a fourth embodiment of the present invention.

FIG. 11 is a view illustrating a schematic configuration of an opticaldisk player according to a fifth embodiment of the present invention.

FIG. 12 is a view illustrating a schematic configuration of an opticaldisk recorder according to a sixth embodiment of the present invention.

FIG. 13 is a view illustrating a schematic configuration of an opticaldisk server according to a seventh embodiment of the present invention.

FIG. 14 is a view illustrating a schematic configuration of an opticalpickup according to the embodiments of the present invention as well asthe prior art.

FIG. 15 is a schematic cross-sectional view of an optical disk deviceaccording to the embodiments of the present invention as well as theprior art.

FIG. 16 is a schematic cross-sectional view of another optical pickupaccording to the embodiments of the present invention as well as theprior art.

FIG. 17 is a schematic perspective view of a multi-layer optical diskhaving two recording layers.

FIG. 18 is a flowchart illustrating a procedure of a focus positionmoving operation upon an interlayer jump operation in a conventionaloptical disk device.

FIG. 19 is a timing chart illustrating variations of respective signalsupon an interlayer jump operation in the conventional optical diskdevice.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

An optical disk device of a first embodiment of the present inventionhas the same basic configuration as that of the conventional opticaldisk device. As shown in FIG. 15, the optical disk device has an opticalpickup 11 equipped with an aberration correcting element (aberrationcorrecting optical system) 4, an aberration correcting element (opticalsystem) driving circuit 8 that drives the aberration correcting element4, a motor 117 for rotating an optical disk 6, and a control circuit 118that receives a signal obtained from the optical pickup 11 and controlsand drives the motor 117, an objective lens 5, the aberration correctingelement (optical system) driving circuit 8, and a laser light source 1.The aberration correcting optical system is not limited to the liquidcrystal aberration correcting element 4 shown in FIGS. 14 and 15, butmay be an aberration correcting lens group 201 shown in FIG. 16, oranother known optical system capable of correcting sphericalaberrations.

An optical disk device and a recording/reproducing method according tothe present invention are effective for the recording (hereinafter“recording” includes “erasure”)/reproduction with respect to amulti-layer optical disk having not less than two recording layers(these may be recording layers with any types such as read-only,write-once, and overwritable layers). However, the recording orreproduction with respect to an optical disk having a single recordinglayer (hereinafter referred to as “single-layer optical disk”) by theoptical disk device of the present invention is not prohibited. Theoptical disk device of the present invention is capable ofrecording/reproducing information to/from both a single-layer opticaldisk or a multi-layer optical disk.

FIG. 1 is a flowchart illustrating a procedure of a focus positionmoving operation and a spherical aberration correcting operation upon aninterlayer jump operation according to the first embodiment of thepresent invention.

In FIG. 1, when the control circuit issues an interlayer jump command(or receives an interlayer jump command from another circuit not shown)while a recording or reproducing operation is being carried out with thefocus control being conducted with respect to a first recording layer(hereinafter referred to as “first layer”) (Step 801), the controlcircuit generates a spherical aberration correction signal and aninterlayer jump signal substantially simultaneously (Steps 802, 803). Anaberration correcting means changes a correction quantity of thespherical aberration to a predetermined value that is set by consideringan adequate correction quantity for a second recording layer(hereinafter referred to as “second layer”) as a destination of the jump(Step 804). At the same time, a focus control means moves the focusposition to the second layer (Step 805). Then, the informationrecording/reproduction is carried out with the focus control performedwith respect to the second layer (Step 806).

Thus, since the spherical aberration correction quantity is changedwhile the focus position is being moved, the spherical aberrationcorrection has been carried out by the time the focus control is carriedout with respect to the second layer. Therefore, the following effectcan be achieved: the focus control is carried out stably, and it ispossible to prevent the focus control from failing due to anunsuccessful interlayer jump.

FIG. 2 is a timing chart illustrating, as an example, how the respectivesignals vary upon the foregoing jumping operation. In FIG. 2, thehorizontal axis indicates time, and the vertical axis indicates voltage.

When an interlayer jump command at Step 801 described above is issuedwhile the focus control is being carried out with respect to the firstlayer, the interlayer jump signal (Step 803 above) and the sphericalaberration correction signal (Step 802 above) vary in response to asignal corresponding to the interlayer jump command as a trigger. Theinterlayer jump signal is composed of a kick pulse KP for leaving a loopfor focus control with respect to the first layer, from whichinformation has been recorded/reproduced until then, and starting tomove the objective lens so that the focus position is moved to thesecond layer, and a brake pulse BP for stopping the moving of theobjective lens so as to enter a loop for focus control with respect tothe second layer. The spherical aberration correction signal has asignal waveform shown in FIG. 2 that is a waveform in the case where thenegative and positive lens groups 21 and 22 constituting the sphericalaberration correcting lens group 201 shown in FIG. 16 are moved byscrew-feeding or another driving technique. In response to a signalcorresponding to the interlayer jump command as a trigger, a voltage forvarying a distance between the negative lens group 21 and the positivelens group 22 is applied to the driving means 25 and 26 until thespherical aberration correction quantity changes from a correctionquantity A that is adequate for the first layer to a correction quantityB that is predetermined.

In the present invention, since the change of the spherical aberrationcorrection quantity is started before the moving of the focus positionto the second layer is completed, that is, before the interlayer jump iscompleted, the spherical aberration correction suitable for the secondlayer has been carried out when the focus control is performed withrespect to the second layer. Therefore, the following effect can beachieved: the focus control is carried out stably, and it is possible toprevent the focus control from failing due to an unsuccessful interlayerjump.

Furthermore, by starting the moving of the focus position from the firstlayer to the second layer substantially at the same time when the changeof the spherical aberration correction quantity is started as shown inFIG. 2, an effect in which an interlayer jump can be carried out withina short time is achieved.

Furthermore, by completing the change of the spherical aberrationcorrection quantity before the moving of the focus position to thesecond layer is completed as shown in FIG. 2, an effect in which thefocus control can be performed more stably is achieved.

In the case where the change of the spherical aberration correctionquantity requires much time, however, the moving of the focus positionmay be completed before the change of the spherical aberrationcorrection quantity is completed, as shown in FIG. 3. By so doing, aneffect in which the time required for the interlayer jump can beshortened further is achieved.

Second Embodiment

The following description will depict a second embodiment of the presentinvention. An optical disk device according to the second embodiment hasthe same basic configuration as that of the optical disk deviceaccording to the first embodiment, and descriptions of the same will beomitted.

FIG. 4 is a flowchart illustrating a procedure of a focus positionmoving operation and a spherical aberration correcting, operation uponan interlayer jump operation according to the second embodiment- of thepresent invention.

In FIG. 4, when the control circuit issues an interlayer jump command(or receives an interlayer jump command from another circuit not shown)while a recording or reproducing operation is carried out with thefocus-control being conducted with respect to the first layer (Step811), the control circuit generates a spherical aberration correctionsignal (Step 812) and the aberration correcting means changes thespherical aberration correction quantity to a predetermined value thatis set by considering an optimal correction quantity for the secondlayer as a destination of the jump (Step 813). Thereafter, the controlcircuit generates an interlayer jump signal (Step 814), and the focuscontrol means moves the focus position to the second layer (Step 815).Then, the information recording/reproduction is carried out with thefocus control performed with respect to the second layer (Step 816).

Thus, since the spherical aberration correction quantity is changedbefore the focus position is moved, the spherical aberration correctionsuitable for the second layer substantially has been completed by thetime the focus control is carried out with respect to the second layer.Therefore, the following effect can be achieved: the focus control iscarried out stably with respect to the second layer without beingaffected adversely by the spherical aberration, and it is possible toprevent the focus control from failing due to an unsuccessful interlayerjump.

FIG. 5 is a timing chart illustrating, as an example, how the respectivesignals vary upon the foregoing jumping operation. In FIG. 5, thehorizontal axis indicates time, and the vertical axis indicates,voltage.

When an interlayer jump command at Step 811 described above is issuedwhile the focus control is being carried out with respect to the firstlayer, the spherical aberration correction signal varies in response toa signal corresponding to the interlayer jump command as a trigger (Step812 above). The spherical aberration correction signal has a signalwaveform shown in FIG. 5 that is a waveform in the case where thenegative and positive lens groups 21 and 22 constituting the sphericalaberration correcting lens group 201 shown in FIG. 16 are moved byscrew-feeding or another driving technique. In response to a signalcorresponding to the interlayer jump command as a trigger, a voltage forvarying a distance between the negative lens group 21 and the positivelens group 22 is applied to the driving means 25 and 26 until thespherical aberration correction quantity changes from a correctionquantity A that is adequate for the first layer to a correction quantityB that is predetermined. Subsequently, the interlayer jump signal varies(Step 814 above). The interlayer jump signal is composed of a kick pulseKP for leaving a loop for focus control with respect to the first layer,from which information has been recorded/reproduced until then, andstarting to move the objective lens so that the focus position is movedto the second layer, and a brake pulse BP for stopping the moving of theobjective lens so as to enter a loop for focus control with respect tothe second layer.

In the second embodiment of the present invention as well, like in thefirst embodiment, the change of the spherical aberration correctionquantity is started before the moving of the focus position to thesecond layer is completed, that is, before the interlayer jump iscompleted. Therefore, the spherical aberration correction suitable forthe second layer has been carried out when the focus control isperformed with respect to the second layer. Consequently, the followingeffect can be achieved: the focus control is carried out stably, and itis possible to prevent the focus control from failing due to anunsuccessful interlayer jump.

Furthermore, in the second embodiment, since the change of the sphericalaberration correction quantity is started before the moving of the focusposition from the first layer to the second layer as shown in FIG. 5,the following effect can be achieved: the spherical aberrationcorrection quantity when the focus position arrives at the second layercan be reduced with certainty, thereby making it possible to perform thefocus control with respect to the second layer more stably.

Furthermore, as shown in FIG. 5, by issuing an interlayer jump signalafter the change of the spherical aberration correction quantity iscompleted, the following effect can be achieved: the focus control canbe performed more stably without being adversely affected by thespherical aberration, when the focus control is performed with respectto the second layer.

However, the interlayer jump signal may be issued so as to start themoving of the focus position before the change of the sphericalaberration correction quantity is completed, as shown in FIG. 6. In thiscase, as shown in FIG. 6, the change of the spherical aberrationcorrection quantity should be completed before the moving of the focusposition to the second layer is completed (that is, before entering thefocus control loop for the second layer). By so doing, the followingeffect can be achieved: the focus control stably can be performed withrespect to the second layer, and moreover, this makes it possible toreduce the time required for the interlayer jump.

Furthermore, in the case where the change of the spherical aberrationcorrection quantity requires much time, the moving of the focus positionto the second layer may be completed before the change of the sphericalaberration correction quantity is completed, as shown in FIG. 7. By sodoing, an effect of reduction of the time required for an interlayerjump can be achieved.

It should be noted that the timing charts shown in conjunction with thefirst and second embodiments described above illustrate, as examples,signal waveforms of the spherical aberration correction signal in thecase where the negative and positive lens groups 21 and 22 constitutingthe spherical aberration correcting lens group 201 shown in FIG. 16 aremoved by screw-feeding or another driving technique. In this case, asshown in the figures, a voltage for varying a distance between thenegative lens group 21 and the positive lens group 22 may be appliedcontinuously to the driving means 25 and 26 in response to a signalcorresponding to the interlayer jump command as a trigger until thespherical aberration correction quantity reaches the predeterminedcorrection quantity B. On the other hand, in the case where theaberration correcting optical system is composed of the liquid crystalaberration correcting element 4 shown in FIG. 14, or in the case wherethe optical system utilizing the spherical aberration correcting lensgroup 201 shown in FIG. 16 includes a magnetic spring as a mechanism formoving the lens group, the voltage of the spherical aberrationcorrection signal is equivalent to the spherical aberration correctionquantity. Therefore, in such a case, the voltage equivalent to thepredetermined spherical aberration correction quantity B may remainapplied continuously as the spherical aberration correction signal afterthe interlayer jump signal is applied, as shown in FIG. 8 (FIG. 8 showsan example of a timing chart of FIG. 5 modified so that the voltageequivalent to the spherical aberration correction quantity B remainsapplied continuously as the spherical aberration correction signal, andthis modification likewise is applicable to the other timing charts).

Third Embodiment

The description of the present embodiment below will depict variousapplication examples of the present invention.

As described above, in the present invention, the change of thespherical aberration correction quantity is started before the moving ofthe focus position to the second layer is completed. Therefore, it ispreferable to determine previously the quantity of a change when thespherical aberration correction quantity is changed. Here, “the quantityof a change in the spherical aberration correction quantity”(hereinafter simply referred to as ♭correction change quantity”) isindicative of a difference between the correction quantity A before thechange and the correction quantity B as an intended value as a result ofthe change).

Generally, the correction change quantity can be set to a differencebetween an adequate correction quantity for the first layer and anadequate correction quantity for the second layer. In other words, thecorrection quantity B preferably is set to the adequate correctionquantity for the second layer.

For instance, the correction change quantity can be determined accordingto a standard thickness of the intermediate layer (the intermediatelayer 65 shown in FIG. 17). In the case of a two-layer disk, thecorrection change quantity can be determined according to a standardthickness of the intermediate layer (thickness between two layers),which is prescribed by the standards. Alternatively, the focus controlmay be performed with respect to each layer upon loading an optical diskin the optical disk device or turning the optical disk device on so thata spherical aberration correction quantity that allows informationsignals to be obtained in the best state is learned for each layer, anda difference between the obtained spherical aberration correctionquantities for the respective layers may be set as the correction changequantity. Preferably, the correction change quantity temporarily isdetermined according to a standard thickness of the intermediate layer,and the focus control is performed with respect to each layer uponloading an optical disk in the optical disk device or turning theoptical disk device on so that a spherical aberration correctionquantity that allows information signals to be obtained in the beststate is learned for each layer, then, the temporarily determinedcorrection change quantity is corrected according to a differencebetween the obtained spherical aberration correction quantities for therespective layers. In the above, the learning of the sphericalaberration correction quantity preferably is carried out with respect toall recording layers of the multi-layer disk, but it may be carried outwith respect to not all the layers, but one, two, or more specificlayers.

Thus, by previously obtaining a correction change quantity necessary foran interlayer jump by leaning, an effect of obtainment of a more stableinterlayer jump can be achieved. By determining the correction changequantity according to a standard thickness of the intermediate layer, itis possible to omit or reduce the learning time. Therefore, an effect ofreduction of a preparation time following the loading of an optical diskor the turning on of the optical disk device can be achieved.

Since the correction change quantity is determined according to astandard thickness of the intermediate layer or according to adifference between the optimal correction quantities of respectivelayers obtained by learning (in other words, the correction quantity Bis set to an adequate correction quantity for the second layer), thespherical aberration correction quantity when the change of thespherical aberration correction quantity is completed is set to thecorrection quantity adequate for the second layer as the destination.Therefore, the focus control with respect to the second layer isstabilized, and the recording/reproduction with respect to the secondlayer can be started immediately after an interlayer jump thereto.

On the other hand, the correction change quantity may be set smallerthan the difference between the adequate correction quantity for thefirst layer and the adequate correction quantity for the second layer.In other words, the correction quantity B may be set to a value betweenthe adequate correction quantity for the first layer and the adequatecorrection quantity for the second layer.

For instance, the correction change quantity may be set according toapproximately half of a standard thickness of the intermediate layerbetween the first and second layers. Alternatively, the focus control isperformed with respect to each layer upon loading an optical disk in theoptical disk device or turning the optical disk device on so that aspherical aberration correction quantity that allows information signalsto be obtained in the best state is learned for each layer, and a valueof approximately half of a standard thickness of the intermediate layermay be used as the foregoing correction change quantity. Stillalternatively, the correction change quantity is determined temporarilyaccording to approximately half of a standard thickness of theintermediate layer, and thereafter, adequate spherical aberrationcorrection quantities for the respective layers are determined bylearning, so that the correction change quantity temporarily determinedmay be corrected according to approximately half of a difference betweenthe obtained spherical aberration correction quantities for therespective layers.

Thus, by setting the correction change quantity to be smaller than adifference between the adequate correction quantity for the first layerand the adequate correction quantity for the second layer, the followingeffect can be achieved: the stability of the focus control with respectto the first layer before an interlayer jump can be secured. Asdescribed in conjunction with the second embodiment, particularly in thecase where the change of the spherical aberration correction quantity isstarted before the moving of the focus position, the focus control withrespect to the first layer possibly is made unstable after the change ofthe spherical aberration correction quantity is started and before themoving of the focus position is started. In such a case, by setting thecorrection change quantity to be smaller as described above, aremarkable effect of the stabilization of the focus control with respectto the first layer and the prevention of the focus control error can beobtained.

It should be noted that, irrespective of which technique among thosedescribed above is used to set the correction change quantity, thespherical aberration correction quantity preferably is re-adjusted againafter an interlayer jump with a change in the spherical aberrationcorrection quantity, so that reproduction signals are obtained in thebest state. By so doing, more stable recording/reproducing operationsare realized.

Furthermore in the foregoing description, the jumping operation withrespect to two layers is depicted as an example, but the presentinvention also is applicable to a multi-layer disk having not less thanthree recording layers.

FIG. 9 illustrates an example of a multi-layer disk having fourrecording layers. The four-layer disk 610 includes, from the opticalpickup 60 side, a substrate 615, an L1 layer (first recording layer)611, an intermediate layer 617, an L2 layer (second recording layer)612, an intermediate layer 617, an L3 layer (third recording layer) 613,an intermediate layer 617, an L4 layer (fourth recording layer) 614, anda reverse-side protective layer 616.

The number of layers of a multi-layer disk is not limited to two orfour, and the present invention is effective and applicable for anynumber of layers not less than two. In the case of the four-layer diskshown in FIG. 9, the first layer as a starting point of a jump and thesecond layer as a destination of the jump in the foregoing descriptioncan be assumed to be any ones of the L1 layer to the L4 layer,respectively. For instance, the present invention is applicable to, notonly the case where the focus position is moved to an adjacent layerlike from the L1 layer to the L2 layer, but also the case where it ismoved from the L2 layer to L4 layer, or the case where it is moved fromthe L4 layer to the L1 layer.

Fourth Embodiment

The following description will depict an embodiment of a computer thatis equipped with the optical disk device according to any one of thefirst through third embodiments, or that uses the recording/reproducingmethod according to any one of the first through third embodiments.

FIG. 10 is a view illustrating a schematic configuration of a computer30 according to the present embodiment. In FIG. 10, 116 denotes anoptical disk device according to any one of the first to thirdembodiments, 35 denotes an input device (for instance, a key board, amouse, or a touch panel) for inputting information, 34 denotes acomputing device including a central processing unit (CPU) that performscomputation based on information inputted through the input device 35,information read out of the optical disk device 116, etc., 31 denotes anoutput device (for instance, a cathode-ray tube, a liquid crystaldisplay device, or a printer) that displays information such as a resultof the computation carried out by the computing device 34.

It should be noted that 33 denotes an input terminal connecting thecomputer 30 and the input device 35, and 32 denotes an output terminalconnecting the computer 30 and the output device 31.

The computer 30 according to the present embodiment thus comprises theaforementioned optical disk device according to the present invention oruses the aforementioned recording/reproducing method according to thepresent invention. Therefore, it is capable of performing an interlayerjump stably and speedily with respect to a multi-layer disk.Consequently, an effect of allowing information recording/reproductionto be performed stably and speedily can be achieved.

Fifth Embodiment

The following description will depict an embodiment of an optical diskplayer that is equipped with the optical disk device according to anyone of the first through third embodiments, or that uses therecording/reproducing method according to any one of the first throughthird embodiments.

FIG. 11 is a view illustrating a schematic configuration of an opticaldisk player 37 according to the present embodiment. In FIG. 11, 116denotes an optical disk device according to any one of the first tothird embodiments, 36 denotes an information-image converting device(for instance, a decoder) for converting information signals obtainedfrom the optical disk device 116 into images, 31 denotes an outputdevice (for instance, a cathode-ray tube, a liquid crystal displaydevice, or a printer) for displaying image information converted by theconverting device 36.

It should be noted that 33 denotes an input terminal provided to theoptical disk player 37, and 32 denotes an output terminal connecting theoptical disk player 37 and the output device 31.

The optical disk player 37 according to the present embodiment thuscomprises the aforementioned optical disk device according to thepresent invention or uses the aforementioned recording/reproducingmethod according to the present invention. Therefore, it is capable ofperforming an interlayer jump stably and speedily with respect to amulti-layer disk. Consequently, an effect of allowing informationrecording/reproduction to be performed stably and speedily can beachieved.

Sixth Embodiment

The following description will depict an embodiment of an optical diskrecorder that is equipped with the optical disk device according to anyone of the first through third embodiments, or that uses therecording/reproducing method according to any one of the first throughthird embodiments.

FIG. 12 is a view illustrating a schematic configuration of an opticaldisk recorder 371 according to the present embodiment. In FIG. 12, 116denotes an optical disk device according to any one of the first tothird embodiments, and 38 denotes an image-information converting device(for instance, an encoder) for converting image information intoinformation that the optical disk device 116 can record.

The optical disk recorder 371 desirably further includes aninformation-image converting device (for instance,-a decoder) 36 forconverting information signals obtained from the optical disk device 116into images, so as to be capable of performing the simultaneousmonitoring upon recording, reproducing information already recorded, andthe like. Furthermore, 31 denotes an output device (for instance, acathode-ray tube, a liquid crystal display device, or a printer) fordisplaying image information converted by the converting device 36.

It should be noted that 33 denotes an input terminal provided to theoptical disk recorder 371, and 32 denotes an output terminal connectingthe optical disk recorder 371 and the output device 31.

The optical disk recorder 371 according to the present embodiment thuscomprises the aforementioned optical disk device according to thepresent invention or uses the aforementioned recording/reproducingmethod according to the present invention. Therefore, it is capable ofperforming an interlayer jump stably and speedily with respect to amulti-layer disk. Consequently, an effect of allowing informationrecording/reproduction to be performed stably and speedily can beachieved.

Seventh Embodiment

The following description will depict an optical disk server 40according to a seventh embodiment while referring to FIG. 13. In FIG.13, an optical disk device 116 is an optical disk device according toany one of the first through third embodiments. A wireless input/outputterminal 39 is a wireless receiving/transmitting device that capturesinformation to be recorded optical disk from the optical disk device 116and outputs information read out of an optical disk by using the opticaldisk device 116 to the outside. By causing the optical disk server 40 tocommunicate information with a plurality of devices having wirelessreceiving/transmitting terminals, for instance, computers, telephones,and TV tuners via such a wireless input/output terminal 39, it ispossible to utilize the optical disk server 40 as an information server(optical disk server) common to these plural devices.

It should be noted that 36 denotes an information-image convertingdevice (for instance, a decoder) for converting information signalsobtained from the optical disk device 116 into images, and 31 denotes anoutput device (for instance, a cathode-ray tube, a liquid crystaldisplay device, or a printer) for displaying image information convertedby the converting device 36. Further, 38 denotes an image-informationconverting device (for instance, an encoder) for converting imageinformation into information that the optical disk device 116 canrecord.

It should be noted that 33 denotes an input terminal provided to theoptical disk server 40, and 32 denotes an output terminal connecting theoptical disk server 40 and the output device 31.

The optical disk server 40 according to the present embodiment thuscomprises the aforementioned optical disk device according to thepresent invention or uses the aforementioned recording/reproducingmethod according to the present invention. Therefore, it is capable ofperforming an interlayer jump stably and speedily with respect to amulti-layer disk. Consequently, an effect of allowing informationrecording/reproduction to be performed stably and speedily can beachieved.

It should be noted that the foregoing description depicts a case wherethe optical disk device 116 is an optical disk device according to anyone of the first to third embodiments, but the optical disk device 116in the present embodiment is not limited to this. Apart from an opticaldisk device according to the present invention, any known optical diskdevice may be used. By combining the optical disk device and thewireless Input/output terminal 39, the following effect is achieved: theoptical disk server 40 can be utilized as a common server for aplurality of devices without wiring.

Though the output terminal 32 is connected with the output device 31 inFIGS. 10 to 13 illustrating the fourth to seventh embodiments, aconfiguration in which the output terminal 32 is provided but notconnected with an output device 31 is feasible as a commercial commodityproduct. Likewise, though the input terminal 33 is connected with theinput device 35 in FIG. 10 illustrating the fourth embodiment, aconfiguration in which the input terminal 33 is provided but notconnected with an input device 35 is feasible as a commercial commodityproduct. Furthermore, though only the input terminal 33 is shown and aninput device is not shown in FIGS. 11 to 13 illustrating the fifth toseventh embodiments, a configuration in which a known input device suchas a key board, a touch panel, or a mouse is connected with the inputterminal 33 is feasible as a commercial commodity product.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments disclosedin this application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1-25. (canceled)
 26. A control circuit of an optical disk device forperforming information recording or reproduction with respect to amulti-layer optical disk that has a plurality of recording layersincluding a first recording layer and a second recording layer that areadjacent to each other, the optical disk device comprising: an opticalpickup including a laser light source, a convergent optical systemhaving an objective lens that receives a light beam emitted from thelaser light source, and converges a microspot on an optical disk, and anaberration correcting optical system that controls a sphericalaberration of the convergent optical system, wherein an operation ofchanging a correction quantity of the spherical aberration is started sothat the correction quantity of the spherical aberration approaches froma value adequate for recording or reproduction with respect to the firstrecording layer to a value adequate for recording or reproduction withrespect to the second recording layer before an operation of moving afocus position of the microspot from the first layer to the second layeris completed.
 27. The control circuit according to claim 26, wherein theoperation of moving the focus position of the microspot and theoperation of changing the correction quantity of the sphericalaberration are started substantially simultaneously.
 28. The controlcircuit according to claim 26, wherein the operation of changing thecorrection quantity of the spherical aberration is started before theoperation of moving the focus position of the microspot is started. 29.The control circuit according to claim 28, wherein the operation ofmoving the focus position of the microspot is started after theoperation of changing the correction quantity of the sphericalaberration is completed.
 30. The control circuit according to claim 27,wherein the operation of changing the correction quantity of thespherical aberration is completed during the operation of moving thefocus position of the microspot.
 31. The control circuit according toclaim 28, wherein the operation of changing the correction quantity ofthe spherical aberration is completed during the operation of moving thefocus position of the microspot.
 32. The control circuit according toclaim 27, wherein the operation of moving the focus position of themicrospot is completed before the operation of changing the correctionquantity of the spherical aberration is completed.
 33. The controlcircuit according to claim 28, wherein the operation of moving the focusposition of the microspot is completed before the operation of changingthe correction quantity of the spherical aberration is completed. 34.The control circuit according to claim 26, wherein a quantity of achange in the correction quantity of the spherical aberration isdetermined based on a standard thickness of an intermediate layerbetween the first recording layer and the second recording layer. 35.The control circuit according to claim 26, wherein a quantity of achange in the correction quantity of the spherical aberration isdetermined based on approximately half of a standard thickness of anintermediate layer between the first recording layer and the secondrecording layer.
 36. The control circuit according to claim 26, whereina quantity of a change in the correction quantity of the sphericalaberration is a difference between a correction quantity of a sphericalaberration adequate for the first recording layer and a correctionquantity of a spherical aberration adequate for the second recordinglayer, which are obtained by learning when the multi-layer disk isloaded in the optical disk device or when the optical disk device istuned on.
 37. The control circuit according to claim 26 wherein aquantity of a change in the correction quantity of the sphericalaberration is approximately half of a difference between a correctionquantity of a spherical aberration adequate for the first recordinglayer and a correction quantity of a spherical aberration adequate forthe second recording layer, which are obtained by learning when themulti-layer disk is loaded in the optical disk device or when theoptical disk device is turned on.